1. Field of the Invention
The present invention relates in general to the field of semiconductor devices and semiconductor processing. In one aspect, the present invention relates to a method and apparatus for sensing or using light in an information processing system.
2. Description of the Related Art
Optical photonic circuits use light to provide high bandwidth, low power, and high speed information transfer, but in order to interface with existing integrated circuits for information processing, the light information must be converted into electrical information that is compatible with such integrated circuits. Prior attempts to develop photon detectors have encountered performance problems that result from the properties of the materials used to manufacture the photon detectors or from the design of the photon detector. For example, silicon-based light detectors are very inefficient at converting light with an energy below 1.1 eV (e.g., greater than approximately 1050 nm wavelength) to charge because of the indirect bandgap associated with silicon. In addition, conventional CCD, CMOS or BJT light detectors are relatively slow (because of the intrinsic RC times that are required to charge and discharge or reset), require too much space (because of the large active area required for such inefficient detectors), lack intrinsic gain, and cannot be used to detect mid-infrared light (because the detector efficiency approaches zero for light wavelengths above 1100 nm). However, because the transparency of bulk silicon allows optical signals to be routed through the silicon substrate, it is expected the first integration of optics into silicon chips will be around 1500 nm wavelength (e.g., approximately 0.8 eV). In addition, the telecommunications industry has perfected many aspects of high bandwidth communication with 1500 nm light, but has done so with detectors that use exotic semiconductor Group III-V materials (such as GaP, GaAs, or InP) which have not been readily and inexpensively integrated with existing CMOS fabrication processes.
Accordingly, a need exists for an improved integrated circuit photon detection device, methodology and system which addresses various problems in the art that have been discovered by the above-named inventors where various limitations and disadvantages of conventional solutions and technologies will become apparent to one of skill in the art after reviewing the remainder of the present application with reference to the drawings and detailed description which follow, though it should be understood that this description of the related art section is not intended to serve as an admission that the described subject matter is prior art.